TECHNOLOGY AREA(S): MaterialsOBJECTIVE: Develop and integrate innovative materials and technologies to enable lowering the operating temperature of high power solid-oxide fuel cells to 300-600 °C.DESCRIPTION: Advanced power sources are needed to provide electric power, which is critical to mission success, to soldiers during long-term missions especially in remote locations.Lightweight Solid Oxide Fuel Cells (SOFC) have been demonstrated that can provide power from gaseous and liquid fuels and offer the potential to provide this power from a wide variety of fuels including complex hydrocarbons, which are generally not amenable for use with other fuel cell technologies.Currently, solid oxide systems are too large, require long start times, and have low cycle lives.This is largely driven by the requirement of operating at very high temperatures (800 -1000 °C) in conventional solid oxide fuel cells.Recent breakthroughs with triple conducing oxide perovskite and double perovskite materials such as BaCo0.4Fe0.4Zr0.1Y0.1O3-δ, NdBa0.5Sr0.5Co1.5Fe0.5O5+ δ, andPrBa0.5Sr0.5Co1.5Fe0.5O5+δ have shown significant promise at low temperatures (300-600 °C) and power densities ranging from 650 to 1100 mW/cm2.Extremely high power densities of 2 W/cm2 at 650°C have been demonstrated from a bilayer-electrolyte LT-SOFC. These remarkable breakthroughs in low-temperature solid oxide fuel cell materials offer an opportunity to develop new high performance 300W LT-SOFC system that is capable of running hydrocarbon fuels, such as propane, and operating at 300-600 °C.This topic is focused on research to develop and integrate these new materials into solid oxide fuel systems to decrease weight and start up times while increasing cycle life.A lightweight (less than 3 kg) 350W+ (>150 W/kg system) low-temperature solid oxide fuel cell system is desired for a multitude of missions ranging from dismounted solider power, UAV power, to silent watch applications. This technology could be used in a variety of roles including: direct power to Army systems or to charge lithium-ion rechargeable batteries which would significantly reduce the logistical burden (weight and volume) for dismounted soldiers by reducing the number of batteries required for extended mission time as well as for a myriad of civilian electronics applications.PHASE I: In phase I a sub scale multicell stack using triple conductive oxide materials will be developed and evaluated using propane fuel. Stack performance data shall be evaluated and preliminary results from the stack should support the potential to develop a 3kg 300W+ system that operates below 600 °C, with a power density above 650 mW/cm2 and specific power150 W/kg.Provide a detailed conceptual design of a 350W+ power system based upon the results generated in these efforts.PHASE II: Based on the results from the successful phase I program, design, construct, assemble and evaluate a high performing 2.5kg 300W LT-SOFC system that operates below 600 °C, with performance degradation 4%/1000h, and lifetime 5000 hours under 350W+ power operation.Power density should be above 650 mW/cm2 and specific power150 W/kg.Pursue the development of a system capable using liquid fuels, such as diesel or JP-8.Deliver 2 units to the Army for evaluation.Assess cost and manufacturability of demonstrated technology.PHASE III: Robust low-temperature SOFC power systems with high power densities will significantly impact both military and commercial applications, accelerating product development, particularly for lightweight portable power devices. Because the market and the number of devices in the commercial sector is much larger than the military market, widespread usage of this technology will drive down the cost of devices for the military. Demonstrate achievements from the SBIR effort to show applicability to field conditions and compatibility with JP-8.Likely sources of funding if the phase III program if successful include: CERDEC, PEO Soldier and PEO Combat Support and Combat Service Support Product Manager Mobile Electric Power SystemsKEYWORDS: Low temperature solid oxide fuel cell (LT-SOFC), Protonic ceramic fuel cell (PCFC), Solid oxide fuel cell (SOFC), Fuel cell, Soldier power.References:Duan, C. et al. Readily processed protonic ceramic fuel cells with high performance at low temperatures. Science 349, 1321–6 (2015); Duan, C. et al. Highly efficient reversible protonic ceramic electrochemical cells for power generation and fuel production. Nat. Energy 4, 230–240 (2019).; Kim, J. et al. Triple-conducting layered perovskites as cathode materials for proton-conducting solid oxide fuel cells. ChemSusChem 7, 2811–2815 (2014).; Choi, S. et al. Exceptional power density and stability at intermediate temperatures in protonic ceramic fuel cells. Nat. Energy 3, 202–210 (2018); Strandbakke, R. et al. Gd- and Pr-based double perovskite cobaltites as oxygen electrodes for proton ceramic fuel cells and electrolyser cells. Solid State Ionics 278, 120–132 (2015).; Vøllestad, E. et al.Mixed proton and electron conducting double perovskite anodes for stable and efficient tubular proton ceramic electrolysers. Nature materials 18, 752–759; S. McIntosh and R. J. Gorte, “Direct Hydrocarbon Solid Oxide Fuel Cells “, Chem. Rev. 2004, 104, 4845-4865.; P. Boldrin, et al,” Strategies for Carbon and Sulfur Tolerant Solid Oxide Fuel Cell Materials, Incorporating Lessons from Heterogeneous Catalysis “, Chem. Rev. 2016, 116, 13633-13684.; E. D. Wachsman and K. T. Lee, “Lowering the Temperature of Solid Oxide Fuel Cells”, Science 2011, 334, 935-939.; J. S. Ahn, et al, “High-performance bilayered electrolyte intermediate temperature solid oxide fuel cells” Electrochemistry Communications 2009, 11, 1504–1507.; Y. Zhang, et al, “Recent Progress on Advanced Materials for Solid-Oxide Fuel Cells Operating Below 500 °C”, Adv. Mater. 2017, 29, Article No. 1700132, 1-33.; J. Patakangas, et al, “Review and analysis of characterization methods and ionic conductivities for low-temperature solid oxide fuel cells (LTSOFC)”, J. Power Sources 2014, 263, 315-331.; L. Fan, et al, “Nanomaterials and technologies for low temperature solid oxide fuel cells: Recent advances, challenges and opportunities”, Nano Energy 2018, 45, 148-176.; A. M. Hussain, et al, “Highly Performing Chromate-Based Ceramic Anodes (Y0.7Ca0.3Cr1-xCuxO3-d) for Low-Temperature Solid Oxide Fuel Cells”, ACS Appl. Mater. Interfaces 2018, 10, 36075-36081.; M. Li, et al, “A niobium and tantalum co-doped perovskite cathode for solid oxide fuel cells operating below 500 °C”, Nature Communications 2017, 8, Article No. 13990, 1-9.
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